Core Practical : Investigsting Macronutrients

Question 1

What nutrient is tested for using iodine solution?

Answer 1

Starch

The color change from orange to blue-black indicates the presence of starch.

Question 2

What reagent is used to test for reducing sugars?

Answer 2

Benedict’s Solution

The test involves adding the solution to a sample and observing color changes.

Question 3

What color change indicates the presence of reducing sugars when using Benedict’s Solution?

Answer 3

Reddish-brown

This occurs after heating the sample in a boiling water bath.

Question 4

What test is used to detect proteins in a sample?

Answer 4

Biuret Test

This test involves potassium hydroxide and copper sulfate.

Question 5

What color change indicates the presence of protein in the Biuret Test?

Answer 5

Blue to violet

The test involves adding potassium hydroxide and copper sulfate to the sample.

Question 6

What test is used to identify lipids (fats and oils)?

Answer 6

Emulsion Test

This test involves ethanol and deionised water.

Question 7

What indicates the presence of lipids in a sample during the Emulsion Test?

Answer 7

Formation of a white emulsion layer

This occurs after adding ethanol and deionised water and shaking the mixture.

Question 8

Fill in the blank: The color change when starch is present is from orange to _______.

Answer 8

blue-black

Question 9

Fill in the blank: The presence of reducing sugar is indicated by a change to _______ when using Benedict’s Solution.

Answer 9

reddish-brown

Question 10

True or False: A blue color in the Biuret Test indicates the presence of protein.

Answer 10

False

A blue color indicates the absence of protein; a violet color indicates its presence.

Question 11

What is the purpose of using a control in experiments?

Answer 11

To ensure we know what a positive and negative result looks like.

Question 12

What is an example of a positive control for the Biuret test?

Answer 12

Anything containing protein (e.g egg white).

Question 13

What is an example of a negative control for the Biuret test?

Answer 13

A solution that does not contain protein (e.g distilled water).

Question 14

Fill in the blank: A positive control for the Biuret test would be anything containing _______.

Answer 14

protein

Question 15

Fill in the blank: A negative control for the Biuret test would be a solution that does not contain _______.

Answer 15

protein